The correct answer is B) Drop the second anchor at the extreme end of the yaw, then adjust the cables until the scope is equal. This is the correct action because dropping a second anchor at the extreme end of the yaw and then adjusting the cables to equalize the scope will help stabilize the vessel and reduce the excessive yawing. The equal scope on both anchors will create a more symmetrical and balanced riding configuration, which is the best way to minimize yawing. The other options are incorrect because: A) Dropping the second anchor without equalizing the scope would not properly stabilize the vessel; C) Simply veering the chain on the riding anchor alone would not be enough to reduce the yawing; and D) Heaving to a shorter scope could make the yawing worse by reducing the vessel's stability.